Radiation therapy is a known treatment for cancerous tumors. Radiation therapy aims to deliver high doses of radiation to tumor volumes. A challenge in treating cancerous brain tumors lies in effectively eradicating the tumor volume while minimizing damage to healthy cells which may be located adjacent or proximate to the cancerous tumor. Conventional radiation treatment is associated with collateral damage to healthy cells. In long term survivors, this may manifest as varying combinations of neurocognitive/neuropsychological problems, endocrine/visual/auditory deficits, impaired bone growth, second malignancies and/or other problems.
Synchrotron-generated micro-beam radiation therapy has been used to treat cancerous brain tumors in small animals. Synchrotron-generated micro-beam radiation therapy uses radiation from a synchrotron source which is collimated to provide a spatially fractionated radiation profile comprising an array of micro-beams. Because of their synchrotron-based radiation source, synchrotron-generated micro-beam radiation therapy uses relatively low energy radiation beams. Synchrotron-generated radiation beams are typically ≤200 keV and are collimated into an array of micro-beams having micro-beam widths in the range of approximately 25-75 μm separated by peak-to-peak separation distances in the range of approximately 100-400 μm.
Synchrotron-generated micro-beam radiation therapy techniques have shown promising results in preserving brain architecture while killing tumor cells in small animal models. In particular, synchrotron-generated micro-beam radiation therapy techniques have shown a higher therapeutic index (ratio of maximum dose tolerated by normal tissue to minimum dose required to control the tumor) than that of conventional radiation therapy methods. Despite the promising results shown in small animal models, the physical characteristics of synchrotron-generated micro-beam radiation therapy techniques limit its use for human patients. Synchrotron-generated micro-beam radiation therapy techniques utilize a low energy photon source (the synchrotron) and micro-beams being made up of such low energy photons have limited ability to penetrate to a sufficient depth within the tissue of humans or other large mammals. The limited depth of penetration associated with the low energy photons of synchrotron-generated micro-beam radiation therapy is not sufficient to destroy tumors embedded deeper in the bodies of humans or other larger mammals. Further, synchrotron radiation sources are often located only in large facilities and such facilities are geographically spaced apart (and thus are not conveniently available). Still further, synchrotron radiation sources are expensive and have rudimentary control systems, which limit the use of these synchrotron sources for medical procedures.
Grid therapy techniques have been suggested for medical linear accelerator (LINAC) based photon radiation in the megavolt energy range. The grid therapy compensator block (or multi-leaf collimator arrangement) has typically been designed to produce a minimum hexagonal array of high dose peaks 1.0 cm in diameter projected at isocenter with a center-to-center grid spacing of 2.0 cm. While LINAC-based grid therapy techniques use X-ray energies high enough to provide sufficient depth of penetration in humans, such large center-to-center grid spacing produced by grid therapy techniques would typically be limited to treating large and bulky tumor volumes, and would not provide a therapeutic index high enough for the treatment of typical brain tumors.
There remains a desire for an apparatus and method for delivery of spatially fractionated radiation treatment that has sufficient depth of tissue penetration for therapeutic use on large mammals, such as humans. More particularly, there is a desire for such radiation treatment to yield a high therapeutic index as may be desired for tumors located in a human brain.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.